Art of crowning floor-joists and apparatus therefor



2 SheetsSheet 1.

(No Model.

- J. FRIEDRIGI-IS. ART OF OROWNING FLOOR JOISTS AND APPARATUS THEREFOR. No. 487,406.

Patented Dec. 6, 1892.

' (No Model.) 2 Sh eets,Sheet 2.

J. FRIEDRICHS. ART OF GROWNING FLOOR JOISTS AND APPARATUS THEREFDR. No. 487,406

Patented Dec. 6, 1892.

g m #1 H J UNITED STATES PATENT GFFICE.

JOSEPH FRIEDRICHS, OF ST. LOUIS, MISSOURI.

ART OF CROWNING FLOOR-JOISTS AND APPARATUS THEREFOR.

SPECIFICATION forming part of Letters Patent No. 487,406, dated December 6, 18912.

Application filed May 2, 1892. Serial No. 431,480. (No model.)

T0 to whom it may concern:

Be it known that I, J OSEPH FRInDRIoHs, a citizen of the United States, residing in the city of St. Louis and State of Missouri, have invented certain new and useful Improvements in the Art of Crowning Floor-Joists and Apparatus Therefor, of which the following is a full, clear, and exact description.

My invention relates to the method of and means for giving to floor-joists the required curvature or convexity to their upper surfaces to compensate for their sag when placed in position and made to support a weight or strain, and has for its object to give each joist in a group of joists to be used together a crowning corresponding to and compensating for their different relative strengths and consequent different relative sags when subjected to a given load or strain, adapting the top surfaces of the different joists to be brought to a common level when thus subjected to such strain or load.

The object in any case of crowning joists is to give the upper surface a convexity or curvature more or less pronounced fromend to end to compensate for the normal sag of the same when supported as a beam at either end. The degree of curvature thus given is determined by the length and should also be modified in each particular piece to indepen dently compensate for the relative deflection resistance of each piece. Heretofore this has been done by hand, the curvature given to the upper surfaces of the joists being uniformly gaged by a templetsimilar for all joists of the same length. It is evident that by this method the joists are all similarly curved and that when placed in position, supported at their ends, the weaker ones will have more of a sag than the stronger ones, leaving the upper floor-supporting surfaces uneven and irregular.

My invention consists in an improved method of crowning joists by which the unequal vertical beam strength of different timbers is provided for, as hereinafter described.

The accompanying drawings, in which like numbers of reference denote like parts in the several figures, serve to illustrate my improved method and one form of apparatus adapted to put the same into practice.

The machine illustrated is a simple woodplaning machine with a longitudinally-movable bed on which to support the timbers to be planed and bring them under the rotating planer-knives, as in an iron-working planer.

Figure 1 is a side elevation of the same. Fig. 2 is a plan view. Figs. 3 and 4: are side elevational views of a joist being planed and after having been planed, respectively; and Fig. 5 is a cross-section taken on the line 5 5 in Fig. 4. Fig. 6 is a vertical section taken parallel to the length of the machine through the rollers and cutterhead, showing the spring-bearings for the rollers in elevation. Fig. 7 is a vertical crosssection on line 7 7 in Fig. 6, and Fig.8 is alongitudinal section on line 8 8 in Fig. 6. Figs. 9 and 10 are views similar, respectively, to Figs. 2 and 1, showing the preferred details of the bearings for the presser-rollers than what is shown in Figs. 1 and 2.

1 l are the side timbers of the machine, to which are secured the vertical standards 2 and in which are formed guideways for the sliding bed-plate 3. In the standards 2 are formed guides for the sliding frame 4:, which is vertically adjustable by means of the screws 5, one of which is placed on either side of the machine and which are connected together by a or0ss-shaft 6 (see Fig. 1) and bevel gearwheels 7, so as to operate both the ends of the frame 4 together. In the frame 4 are revolubly mounted the forward and following rollers 8 and the rotary knife-shaft 9, to the end of which, as shown in Fig. 2, is secured the small drive-pulley 10, by which means the machine as a whole is made to operate through the medium of the belt 11. It will be readily understood without more detailed illustration that in the operation of the machine at the same time that the knife-shaft 9 is made to rotate the bed-plate or platform 3 is given a longitudinal movement to bring the joists 12 in operative position under the rotating knives.

The foregoing description relates to the form of machine illustrated in the first and second figures in the drawings. While by the use of the machine as just described and as illustrated in the first two figures the crowning, as hereinafter described, can be effectively carried out, yet the details illustrated in Figs. 6 to 10, inclusive, and hereinafter deof the upper spring 17.

scribed are preferably made use of to more conveniently and, strictly speaking, more effectually carry out my method in practice. These details, indeed, are common to machines to which my method is adapted and form no part of this invention, but are preferably made use of in the practice of my improved method.

The rollers 8 are journaled in boxes 16, which are provided guideways in the vertically-movable frame 4, the boxes being held in vertically-yielding position by the compression-springs 17 and 17 and this position made adjustable by means of the adjustingscrews 18, which bear against the upper end The normal position of the journal-bearing is in this manner de termined as aposition of equilibrium between the two springs, and this decided by the tension given to the upper springs by the set or adjusting screws 18. By these means the level of the under or effective side of the rollers 8 and the cutting-level of the cutter 9 are adjustable relative to each other. The cuttaken by the knife is in any instance therefore defined, primarily, by the set position of the forward roller 8. Thus when the supporting. frame, is screwed down to bear harder on the timbers or, what is the same thing, the timbers press harder on these rollers, as hereinafter explained,in the act of planing the upper spring will give more or less and the cutter will take a deeper bite.

As illustrated, there are preferably (for economic reasons) several (six) joists l2 placed on the sliding platform 3 and secured together by the clamps 13. Instead of laying the joists fiat on the plane surface of the sliding platform 3 I interpose under each end of the joists a block 14 thick enough to raise thejoists far enough away from the surface of the planerbed or platform 3 when the joists are carried in under the action of the knife to be planed, as illustrated in Fig. 3, to allow for the neoessarily-consequent deflection of the middle portions of the joists. This result might also be obtained by hollowing the bed of the planer to similarly allow for the deflection of the joists. In this manner the joists-in fact, each individual joist independently of the other are in the operation of crowning subjected toa strain similar to that when placed in a building, similarly applied, and under exactly similar conditionst'. e.,the ends only supported.

As already stated, the amount of cut of the knife 9 is due, primarily, to the relative position of the cutter-blades and the normal position of the forward roller 8, but not altogether so. \Vhen, for instance, in the act of planing the frame 4. is screwed down, so that the ends of the timbers, when they are supported at their ends only, are immediately below the cutter-head, the roller is forced upward relative to the cutter, and therefore the cut taken will be greater at this point than at the middle when it comes under the cutter in that the timbers give and do not press so hard against the rollers 8, allowing them by the action of the upper springs 17 to be depressed relative to the cutter.

It will be evident that the curved form of surface of the upper edge of the joists illustrated in Fig. 4. will be the result of passing the joists in under the knife and rollers in that, the ends being supported, the knife will take out a given out there, which cut will be reduced as we approach the middle portion of the length of the joists, the joists being deflected from the normal by the pressure applied in a vertical direction by the knife and rollers, or, what is the converse of this fact, if

the joists were rigid beams without defiec-' tion the cut would be even throughout the length of the same. Moreover, this decrease of cut at the mid-length of the timbers being due to the deflection of thejoists as beams supported at each end for a given pressure, the stronger onesi. e., those better able to resist this applied strainwill give less and be cut more in the middlethat is, they will be cut more nearly to a straight linethan the weaker ones, which give more to the applied strain. There is more than one cause that goes to effect this result. the primary cause of the crowning of the group of joists, considered collectively, is due to the decrease of upward pressure of the joists in their mid-length on the presser-roilers; but this in itself does not account for the differential planing of individual weaker and stronger timbers. Consider, for the sake of illustration, the pressure-rollers removed. Then, the cutteritself bearing against the upper surfaces of the joists, as they are supported at their ends only, the joists will give more or less before the revolving knife, and that in each individual joist in the inverse proportion to its strength and its ability to resist the deflecting strain put upon it by the cutterthat is, at the middle of their length they will be out less than at their ends, and that to a different degree as between weaker and stronger ones. Now when the roller (the preceding one, which is the only one that need be considered) is used the strain is partly borne by the roller and partly by the cutter, and, while the result, as above, when the roller was removed, will not be so marked, yet it is effected to a comparative degree. It has also been observed in the practical use of the planer as described, where the roller is smallnot more than two and one-half or three inches in diameter-it becomes more or less, in proportion to the pressure put upon it, embedded in the fiber of the timber, and this of course, modified by the strength of the individual joist, in this manner presenting more timber to the cutter than if it was not embedded and of course comparatively more for the stronger timbers. Now when this applied strain is removed and the joists allowed to assume their normal position their upper surfaces at their mid-lengths will be brought to relatively different heights, the weaker ones,

As before stated,

as shown in Fig. 5, those which were less able to resist the deflecting strain put upon them in the planer, being the higher. When this strain is again applied, as would be the case when the joists are put into service, as to support a floor, they will be again brought to a common level. It is evident that when the joists are supported at their ends only they at once assume a normal position of deflection due to their own weight and that this enters into and is compensated for by the method described, especially inasmuch as they are placed during the act of crowning in their natural positionthe one in which they are to be used. This natural deflection also undoubtedly helps in a small measure to obtain the results effected.

It is in this particular that I claim the superiority of my improved method in practical results over any in use l1eretofore-in that the joists are planed to a flat surface when they are being subjected to what can be considered conditions exactly similar to what they would be subjected when used in actual practice.

It will be evident that, while, as already stated, the essential feature of invention in the apparatus used to carry out my method is the supporting of the joists at their ends only, these details relate merely to this particular means of carrying my method into practice-that is, when the deflecting pressure is applied by the means itself by which the surface of the joists is planed or leveled off it is enough to support the joists in such a position to allow these forces to act. The principal being disclosed, it is obvious that other means might be devised to effect the results obtained. For instance, the joists might be deflected by means other than the presser-roller and the cutter and means other than the revolving cutter be used to level the surface while the joists are thus deflected.

1. The method herein described for crowning floor-joists, which consists in subjecting the same to a deflecting strain and leveling one surface while so subjected, substantially as and for the purposes described.

.3. The method herein described for crowning floor-joists, which consists in supporting the same at their ends and planing or otherwise leveling the upper surfaces of the same, substantially as and for the purposes described.

3. In a machine for crowning floor-joists, the combination,with the leveling-cutter, of a supporting and carrying platform and means for deflecting the stock while it is being operated on by the cutter, substantially as and for the purposes specified.

4. In a machine for crowning floor-joists, the combination, with the cutter, of a supporting and carrying platform and means supported directly by and carried with the platform by which the joists are supported at their ends only, substantially as and for the purposes specified.

5. In a machine for crowning floor-joists, the combination, with an adjustable cutter, of a supporting and carrying platform provided with means for supporting the stock away from the platform, thereby permitting the joists to be deflected while being cut, substantially as and for the purposes specified.

6. As a new article of manufacture, a crowned floor-joist bellied on one side, said bellied portion being formed by planing or otherwise leveling one surface of the joist while it is being deflected from the normal, substantially as and for the purposes specified.

In testimony whereof I have affixed my signature, in presence of two witnesses, this 27th day of April, 1.892.

JOSEPH FRIEDRICH-IS.

Witnesses:

A. RAMEL, WM. A. BAUKELER. 

